An oscillator used in a low-power transmitting unit such as an automotive UWB radar interrupts an output of a quasi-millimeter-wave (22 to 29 GHz) oscillation signal by an external pulse signal representing a transmission timing of a transmitting radar signal.
FIG. 10 shows a configuration of a conventional radar oscillator 10 of this type.
In FIG. 10, an oscillator 11 has an amplifier 12, a resonator 13 connected to an output section of the amplifier 12, and a feedback circuit 14 which feeds back positively an output signal from the amplifier 12 to an input side to oscillate a signal having a frequency determined by a resonant frequency of the resonator 13.
An oscillation signal output from the oscillator 11 is input to a switch 15 constituted by an electronic switch obtained by a semiconductor device turned on or off by a pulse signal P representing a transmission timing of a transmitting radar signal.
When the pulse signal P for switching the switch 15 is set at one level (for example, a low level), the switch 15 is turned on to output an oscillation signal S. When the pulse signal P is set at the other level (for example, a high level), the switch 15 is turned off, and does not to output an oscillation signal S.